how to convert images to 16-bit byte array (4.7-inch E-ink display for ESP32-S3)

Hi All,

I bought the 4.7-inch E-ink display for ESP32-S3 and it can display the sample images nicely but I can't find a way to convert an image to a greyscale byte array. There are online versions that convert to black and white.

Are there any native supported image formats?

Any suggestions?